1. Technical Field
The present invention relates to an image forming apparatus having a power saving function.
2. Related Art
Recently the image forming apparatus having a power saving function is widely used in printers and copying machines. For example, it is known that a controller including a determination unit and an automatic setting unit. For a parallel interface control circuit, a serial interface control circuit, a network interface control circuit, and the like which are of the communication interface control circuit, the determination unit determines whether a computer is connected to each of communication interface control circuits or not. When the determination unit determines that the computer is not connected to the communication interface control circuit, the automatic setting unit individually sets the communication interface control circuit in a power saving mode. In the controller, negotiation is required for the connection between the communication interface and the computer, and it is determined whether the connection with the computer is completed or not according to the negotiation status. When a signal is inputted to the interface switched to the power saving mode, the power saving mode is automatically released.
In a peripheral device (for example, printer), such as USB (Universal Serial Bus) and IEEE (American Institute of Electrical Engineers) 1394, which has the communication interface including a power line for indicating a potential a predetermined value or more when the communication is enabled, for example, it is known that a peripheral device which monitors the potentials of the power lines of the communication interfaces and the energy saving of the peripheral device is performed when the potential of the power line is decreased a predetermined value or less.